Looking for a new battery charger

[Toubab]

Hi everyone. I'm still relatively new to most things electrical on board my boat but I have been learning really fast. I'm thinking of replacing my battery charger in the near future and was looking for some help.

My current set up is a Sentry G120-3NL battery charger (that I've had a tough time finding info on), a normal lead acid house batt, and an AGM starting batt. The boat had some sort of battery combining diode when I bought it but it was so corroded that I took it out. I've just been manually switching the banks on or off as needed to keep them from draining each other and everything. Even with a diode/combiner/whatever, my understanding is that with the batteries each having a different chemistry one would be getting over-charged and one under-charged since I have to put them on the same charging regime, correct? Chargers that can handle more than one bank would allow me to keep the batteries isolated from each other, getting rid of the need for the combiner, also correct?

So anyway, I'm looking at some new chargers and reading through some online resources and Nigel Calder's books and I think I know what I'm looking for. I'm also trying to keep in mind a future upgrade to a LiFePo house battery.

I need a charger with independent sensors and charging regimes for each battery (it's been hard to tell sometimes from online descriptions whether or not they have this). I'd also like it to be able to intelligently share the load between batteries (ie a 20 amp charger that will give 10 to each until one is full, then the full 20 to the other). And it will be run off of a generator when away from the dock so it has to be able to handle the noisy output from the generator. Then of course whatever other features to make it an all around good charger.

I found this charger: Xantrex / Schneider TRUECharge2 40A Battery Charger that seems to fit the bill. My thought being that in the future I could add the remote panel: Xantrex / Schneider TRUECharge2 Remote Panel which would give me more control to adjust the charging regime for a LiFePo bank, plus the ability to piggy back another charger and take advantage of the lithium's high charge acceptance.

Then there's also this one: ProMariner ProNautic 1240P Digital Performance Battery Charger and this one: MDP Electronics Premium Battery Charger which both say they have factory settings for lithium batteries.

Anyway, those are my thoughts so far and I'm looking for any other suggestions or general guidance. Thanks!

[Boracay]

You don't say what the output on your Sentry charger is or how big your house batteries are so I'll make a few assumptions.

Assuming you have 200 Amp/hour capacity in your house batteries and you discharge to the 50% level then you'll want to be returning that fairly quickly. A 40 amp charger could do it, but more would be better, particularly if running off a generator.

If you have more than 200 amp/hours of house battery then a bigger charger becomes more important. Don't forget that the charge rate drops as the batteries near full charge.

If the start battery is only used to start the engine then this only uses a small part of the capacity. A small charger could do the trick. I have two 10 watt solar cells charging my start battery through a basic controller and this seems to work just fine. Don't forget the alternator will do most of the charging when the engine is running.

I've also set up an Echo Charge so that the alternator charges the house batteries first and then the start.

So why not connect the Sentry to the house batteries only and just get a small intelligent charger for the start. Worry about upgrading the charger when you upgrade the batteries.

[skipmac]

I'm not aware of a charger that will put out different charging routines for different batteries at the same time. Not saying one isn't out there but I haven't seen one.

But here's a question. I assume at some time you will go sailing and not be connected to shore power. So what will you do then to charge two different types of batteries? Will you have two different alternators on the engine? Will you have two separate solar panels? Two different wind generators?

I think it would be simpler and cheaper in the long run to keep house and starting batteries of the same type and just use an echo charger to keep the starting battery isolated but topped off every time you're charging the house batteries.

[Octopussy]

Toubab,

We're in the middle of refitting our boat, and originally we were looking at a Xantrex. BUT...

We have a friend that (we found out) used to be a Xantrex dealer here in Annapolis, and he told us NOT to buy one. His reasoning was that they are a sealed unit. If one component fries, then you have to buy an entirely new Xantrex.

He recommended a MagnaSine. You can buy the components, and they can be repaired. So that's what we're planing to buy.

Cheers,
Octopussy

______________________________
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[Sailor Doug]

No not buy a Xantrex! I did and went through 4 units to get one that worked.

[sailcruiser]

I've been happy with my Victron. I was between the Victron or a Mastervolt based on suggestions from people educated on the subject.

SC

[truant]

i went through 3 Xantrex units this past year and gave up on them. I switched to a Promariner unit and have been very pleased.

[Toubab]

Originally Posted by Boracay

You don't say what the output on your Sentry charger is or how big your house batteries are so I'll make a few assumptions.

Yea I don't actually know those values for sure. Like I said, I've had trouble finding any info on the Sentry charger. I don't have a manual for it and can't find one online either. What would be a good way to test it's output? Let the batteries drain a good bit then just measure the amperage?

The house battery I just replaced with the same thing that was there when I bought the boat. I brought it into the shop and asked for another and the guy there couldn't tell me the capacity...

So why not connect the Sentry to the house batteries only and just get a small intelligent charger for the start. Worry about upgrading the charger when you upgrade the batteries.

I'm leaning towards doing this I think. Any recommendations for a good, inexpensive charger that would work for this set up?

Originally Posted by skipmac

But here's a question. I assume at some time you will go sailing and not be connected to shore power. So what will you do then to charge two different types of batteries? Will you have two different alternators on the engine? Will you have two separate solar panels? Two different wind generators?

I think it would be simpler and cheaper in the long run to keep house and starting batteries of the same type and just use an echo charger to keep the starting battery isolated but topped off every time you're charging the house batteries.

Here's my planned set up, still putting some things together but I think you'll get the picture: AGM battery bank to start the engine, start the AC generator, and run the windlass. Charged from an AC charger of some sort and the alternator with a switch to only let the windlass operate when the engine is running (probably with a manual override in case of emergencies). LiFePo house bank charged from an AC charger plus any alternative energy sources I have (solar, wind, etc). Possibly add a second, high output alternator to the engine to charge the house bank, and possibly/probably have an inverter/charger, but these things would be quite a bit down the line.

With this set up, the engine/windlass bank should be getting topped off whenever it's being used, plus whenever there's plenty of AC power to go around, and the house bank will be getting charged from every available source.

As far as having different chemistries for the different banks, it sure would be simpler, cheaper probably not, not with the extra life and everything of LiFePos. And definitely not as practical or effective. I know I'm not the only person who wants a different type of house and starting battery.

Thanks for all the help! Looks like I won't be getting a Xantrex! lol

[kbudd]

I have a Xantrex true charge 40 and have not had any problems with it. It will not charge 2 different battery types. I am replacing it with an inverter charger this spring so if you are interested in it, I will sell it cheap. PM me if interested. I also have the remote panel and temperature sensor.

[zeehag]

xantrex are rebuildable in mexico. folks have found. the current at docks here isnot 120v--is more like 137, and fries xantrex units nicely, so folks have had to have them rebuilt/replaced.

i am still seeking an antique green new mar unit, 3 in one with transformer, charger and galvanic isolator in one machine, just like the unit that used to be on board--is about 40 pounds.

[Toubab]

Bump to see if anyone can recommend a small charger to charge just the engine battery like I described above...

[Pete7]

Why do you want to charge the engine battery? If its isolated why you are sailing or anchored it will be good for a month before needing a charge, then just run the engine.

However, if you absolutely must have a second charger, how about something simple and small from the CTEK range:

CTEK - Car Battery Chargers, Marine Chargers and Solar Battery Chargers

Pete

[Crimea Cruiser]

Originally Posted by Toubab

Bump to see if anyone can recommend a small charger to charge just the engine battery like I described above...

A smaller charger? I use twin gerbils on dual inline treadmills, but the cost of keeping fresh lettuce onboard for them is having me thinking of switching systems. Plus, none of the crew ever want to teach them how to use the head, to save from changing litter so often.

[Crimea Cruiser]

Seriously though, you can try a Iota 55 a 740 watt 12 volt charger. you can set maximum voltage points at either 14.8 or 15.4.
They are half the price of the Xantrex and carry same length of warranty. ( downside is they are not 3 stage or have float function )

[Crimea Cruiser]

and nor are they sealed units.